Process, Controls & Plant Focus on: Seals, Bearings & Lubrication 24 | Plant & Works Engineering www.pwemag.co.uk August/September 2025 The choice of bearings in machinery design significantly affects performance, durability and cost. Bearings are essential for reducing friction, supporting loads and allowing smooth operation of moving parts. With the rise in demand for highly specialised machinery and growing interest in custom manufacturing, engineers often face a critical decision - selecting custom bearings tailored to their application or opting for readily available off-the-shelf solutions. Chris Johnson* weighs up the advantages and disadvantages. Should you opt for custom or off-the-shelf bearings? For engineers working under tight deadlines or within budget constraints, off-the-shelf bearings often provide the most practical solution. These bearings are mass-produced, ensuring consistent availability and significantly reducing lead times compared to custom alternatives. Their largescale manufacturing also benefits from economies of scale, lowering costs without compromising quality. What’s more, off-the-shelf bearings undergo rigorous standardisation and testing to meet industry standards, like ISO 281, bearing life calculation and ISO 492, tolerance classes for rolling bearings. Compliance with these standards ensures predictable performance and reliability across a wide range of applications, from industrial machinery to aerospace systems. Another key advantage of off-the-shelf bearings is their versatility. With a broad range of options designed to accommodate different loads, speeds and environmental conditions, they are widely used across industries, including automotive, medical and manufacturing sectors. When custom bearings are necessary While off-the-shelf bearings are suitable for many applications, some scenarios require a more tailored approach. Custom bearings are specifically designed to meet unique specifications such as non-standard sizes, extreme operating conditions or specialised load capacities. The aerospace industry is increasingly using custom parts and components to enable more diverse and specialised aircraft designs. For instance, industries like aerospace and medical devices often require bearings with high precision — meaning tight dimensional tolerances, low friction and consistent rotational accuracy. These bearings must also be resistant to harsh environments and capable of functioning under high speed or heavy load conditions. Custom bearings allow engineers to address these challenges, ensuring optimal performance and durability. However, custom solutions come with trade-offs. The design and manufacturing process often require significant time and investment, resulting in higher costs and longer lead times. Engineers must carefully evaluate whether the added benefits of custom bearings justify these challenges. Custom or off-the-shelf — how do you decide? When making the choice between custom and off-the-shelf bearings, it is crucial to assess several key factors to ensure the most suitable choice for your application. First, consider the specific requirements of your application. Are there unique operating conditions - such as high temperatures, unusual loads or non-standard dimensions — that off-theshelf bearings may not be able to address? If the answer is yes, then custom bearings may be the better option. Next, evaluate the project’s budget. Custom bearings often involve higher manufacturing and design costs, so it’s important to determine whether the additional expense aligns with any financial constraints. Alongside costs, lead time is another consideration. Deloitte reported in its 2025 Manufacturing Industry Outlook that despite lead times have shown improvement since prepandemic levels, global supply chain disruptions persist. It predicts that companies are expected to face continued supply chain risk in 2025, due to factors like geopolitical tensions, labour shortages and rising input costs. Custom bearings typically require longer production timelines, which could impact your overall schedule. If a faster turnaround is
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